Afternoon Peak Period Research Articles

Assessing Traffic and Emergency Benefits of Railroad Grade Separations

The benefits of constructiong grade separations at four railroad crossings in Thunder Bay, Canada, are evaluated. The purpose of the study is to determine the two crossings whose grade separations provide the most efficent traffic operations and maximum accessibility of emergency services (fire stations and hospitals). Efficiency is evaluated by several measures of performance including travel time, delay, and fuel consumption. Accessibility is evaluated by the travel time between the emergency services locations and various areas in the city. Traffic volume data were collected in May 1985 during the afternoon peak period (4:30-5:30 P.M.) for 15-minute intervals. These data, along with other data related to land uses, are used to establish the origin-destination (O-D) demands through the use of a recently developed model, LINKOD. These O-D demand and the characteristics of the network represent the basic input to a traffic management model, CORCONF. The CORCONF model is used to evaluate the impacts of various grade-separation alternatives on both efficency and accessibility. In addition to analyzing a real-world problem, this paper also discusses some aspects related to the application of the models described herein, which should prove useful for potential users of the models.

Evaluation of signal timing and parking strategies on a signalized urban arterial

A computer model for traffic signal coordination, TRANSYT-7F, was applied to a signalized urban arterial in the city of Thunder Bay. The purpose of this application was to develop an optimal coordinated signal timing for the arterial. The study arterial consisted of five intersections and extended over a distance of 1.2 km. Observed traffic volumes and their direction of movement were collected during an afternoon peak period (4:00 p.m. to 5:00 p.m.) in September 1983. Data on existing physical configuration and signal system characteristics were also collected and modelled for input to TRANSYT-7F. Seven improvement strategies concerning changes in the existing signal system and regulatory conditions were evaluated and compared to existing conditions (do-nothing). Several measures of effectiveness generated by TRANSYT-7F were used as the basis for evaluation, which included travel time in the system, delay, fuel consumption, and a performance index, which is a function of delay encountered in the system and the number of stops.The results showed that the best strategy was to implement a common cycle of 52 s for the entire system. This is opposed to the existing 80 s network-wide cycle length. This strategy optimized the corridor with parking prohibitions on both sides of the arterial, and two phases per cycle at all intersections. The best strategy improved all measures of effectiveness. In particular, a reduction in the magnitude of 36% in the performance index was observed, along with a predicted decrease in fuel consumption of 21%. Key words: signal timing, coordination, arterial, traffic, management, parking, evaluation, computer model, delay, fuel consumption.

Time Series Models for Freeway Incident Detection

An autoregressive integrated moving average model of the form, ARIMA (0,1,3), is presented for describing the stochastic and dynamic behavior of freeway traffic volume and occupancy observations. The model is applied to the detection of freeway capacity-reducing incidents through the sudden and pulsed changes they generate in traffic stream time series data. An incident is detected if the observed value of traffic occupancy lies outside the probability limits constructed two standard errors away from the corresponding point forecast. The developed ARIMA occupancy algorithm has been found superior to the exponential and the California algorithms in terms of detection rate, false alarm rate, and mean time lag to detection. The analysis is based on surveillance data recorded at the Los Angeles, Minneapolis, and Detroit freeway systems during the afternoon peak periods.